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Calcium-entry blockers during porcine cardiopulmonary resuscitation
M von Planta1, M H Weil, R J Gazmuri
1Department of Medicine, University of Health Sciences, Chicago Medical School, Illinois.
Insights
Calcium-entry blockers like verapamil and diltiazem did not improve survival rates during cardiac arrest in pigs. Coronary perfusion and CO2 levels during CPR were key predictors of resuscitation success, not the drugs themselves.
Area of Science:
- Cardiology
- Emergency Medicine
- Pharmacology
Background:
- Calcium-entry blockers can improve myocardial pH and decrease PCO2 in ischemic conditions.
- Previous evidence on their efficacy in improving myocardial acidosis and resuscitability during cardiac arrest is limited.
Purpose of the Study:
- To compare the effects of verapamil and diltiazem versus placebo on myocardial acidosis and resuscitability during cardiac arrest and cardiopulmonary resuscitation in a porcine model.
Main Methods:
- A porcine model of cardiac arrest and cardiopulmonary resuscitation was used.
- Animals received either verapamil (0.05 mg/kg), diltiazem (0.075 mg/kg), or saline placebo.
- Coronary perfusion, aortic pressures, end-tidal CO2, and intramyocardial pH were monitored.
Main Results:
- Resuscitation rates were similar across groups: 6/11 (verapamil), 5/10 (diltiazem), and 6/10 (placebo).
- Coronary perfusion pressure and end-tidal CO2 during chest compressions predicted resuscitation success, independent of treatment.
- Neither verapamil nor diltiazem significantly altered coronary perfusion, attenuated intramyocardial acidosis, or improved resuscitability.
Conclusions:
- Verapamil and diltiazem did not demonstrate a significant benefit in improving myocardial acidosis or resuscitability in this porcine model of cardiac arrest.
- Hemodynamic parameters during cardiopulmonary resuscitation are critical predictors of successful resuscitation.
Abstract:
1. Calcium-entry blockers increase the intramyocardial pH and decrease the intramyocardial Pco2 of ischaemic canine myocardium. However, the evidence documenting improvements in myocardial acidosis and in myocardial resuscitability after administration of calcium-entry blockers during cardiac arrest is incomplete. We therefore compared the effects of verapamil (0.05 mg/kg) and diltiazem (0.075 mg/kg) with those of saline placebo in an established porcine model of cardiac arrest and cardiopulmonary resuscitation. 2. After verapamil, six of 11 animals were successfully resuscitated; after diltiazem, five of 10; and after saline placebo, six of 10. Coronary perfusion and mean aortic pressures together with end-tidal CO2 concentration during precordial compression were predictive of resuscitation, independently of the drug or placebo. 3. Coronary vein pH decreased to 6.91 +/- 0.06 units (mean +/- SEM) with concurrent increases in PCO2 to levels exceeding 100 mmHg. Coronary vein lactate increased to a maximum of 7.5 +/- 0.6 mmol/l. Coronary vein acidaemia was accompanied by decreases in intramyocardial pH to 6.64 +/- 0.06 units. However, each of these differences between success and failure of resuscitation was unrelated to treatment with calcium-entry blockers. 4. Accordingly, neither verapamil nor diltiazem selectively altered coronary perfusion pressure, attenuated intramyocardial acidosis or improved resuscitability after porcine cardiac arrest and cardiopulmonary resuscitation.